Browsing by Author "Abdullah, Oday"

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An Investigation of the Suspension Characteristics of the Line Model of the Vehicle Using the Taguchi Method
(2022) Stojanovic, Nadica; Jweeg, Muhsin; Grujic, Ivan; Petrovic M.; Muhsen S.; Abdullah, Oday
It can be considered that the suspension system is one of the most important systems in the VEHICLE. Where it is responsible for the stability and balance of the vehicle's structure on the roads and curves to ensure the comfort of passengers. Also, it absorbs the shocks resulting from the unevenness of the road and prevents it from reaching the wheelhouse. The influence of the suspension constructive parameters in order to obtain the smallest level of displacements of the sprung mass has been investigated. The following control parameters are the stiffness of the sprung, unsprung mass, and the damping of the sprung mass. The parameter which affects most displacements of the sprung mass was determined by applying the analysis of variance (ANOVA). The investigation was conducted using MATLAB/SIMULINK software, and a line model of a quarter of the vehicle was created. It was determined that the stiffness of sprung has the most significant influence on the displacement of the sprung-mass, which further affect the vehicle's comfort.
Application of New Technologies to Improve the Visual Field of Heavy Duty Vehicles Drivers
(2020) Stojanovic, Nadica; Grujic, Ivan; Glišović, Jasna; Abdullah, Oday; Vasiljević, Saša
© 2020, Springer Nature Switzerland AG. The World Health Organization has declared pedestrians, cyclists and motorcycle, moped drivers and passengers, as vulnerable categories of participants in traffic. Some of the reasons are that they often can be found in a blind spot of the cars, vans and heavy duty vehicles. Therefore, the drivers of such vehicles can t notice them. Determination of the visual field of heavy duty vehicles drivers, is performed in the paper by applying Catia V5 software, module Ramsis (in case if only rear-view mirrors are used). Based on this approach, the reasons for using cameras and sensors instead of a rear-view mirror are reflected in the reduction of blind spots and reduction of the aerodynamic drag coefficient, the numerical simulation was obtained by using Ansys/Workbench 14.5 software.
The determination of the disc brake thermal stresses for different vehicle speeds
(IOP Publishing, 2022) Stojanovic, Nadica; Grujic, Ivan; Abdullah, Oday; Belhocine, Ali; Glišović, Jasna
From the aspect of traffic safety, the brake system is one of the most important systems. For all exploitation conditions, for which vehicles are projected, and for loads in prescribed boundaries, no matter to the vehicle speed, it is important, for the brake system to be reliable and to provide a very fast stop, or speed adjustment to road conditions. During the stop or during the speed adjustment it comes to the disc brakes temperature increment. So, because of this, the experimental investigations were conducted, in order to determine final values of the temperature for multiple braking processes until stop. In this paper, were conducted two experimental tests for the same vehicle, but for different speeds, which were 60 km/h and 80 km/h, while the other parameters (initial temperature, the mass of the simulated vehicle, number of repetitions) were the same for both tests. The conclusion is that by increment of the speed, rises the necessary time to stop the simulated vehicle, and by this, rises and the stopping distance. Also, rises and the temperature of the disc brake, with the increment of the vehicle speed.
Effect of Rear Spoiler Shape on Car Aerodynamics and Stability
(2020) Stojanovic, Nadica; Miloradović, Danijela; Abdullah, Oday; Grujic I.; Vasiljević R.
© Springer Nature Switzerland AG 2020. Computational dynamics is widely used when designing cars in order to obtain the optimum design and reduce the time and costs. Car design plays the main key in decision on purchasing the car. Car manufacturers have a very difficult task which is build a car that will be attracted potential buyers with its design, which does not deteriorate the car’s aerodynamics or has the stability at high level of speeds. In order to enhance the car’s stability, it’s necessary to add the rear spoilers to the car body. This paper presents deep study for effects of fitting different types of rear spoilers on the car’s aerodynamics and stability. Determination of corresponding aerodynamic drag and lift coefficients was performed using ANSYS software 14.5/Fluid Flow CFX module. It was found that the aerodynamic drag coefficient increased slightly with (3.4%) when fixed the rear spoilers, but a considerable reduction of the aerodynamic lift coefficient value (around 32%).
Investigation of the penetration and temperature of the friction pair under different working conditions
(2020) Stojanovic, Nadica; Abdullah, Oday; Schlattmann J.; Grujic I.; Glišović, Jasna
© 2020 Published by Faculty of Engineering. The phenomenon of vehicle braking is very complex, because during the braking process, the heat will be generated on the braking disc and the braking pads. This will cause the penetration in the contacting surfaces. In this research paper, three-dimensional model is developed and validated using finite element technique. It was used ANSYS/Workbench 14.5 software, Transient Structural module to achieve the numerical analysis. During the stopping process, the high temperatures appeared on the braking pads, where the temperature exceeded 150 ℃ when applied pressure is 0.9 MPa. While, when the applied pressure is 1.1 MPa the temperature on the contact surface is exceeded 180 ℃, after just 1.3 s. The important conclusion based on the results is the most significant factors on the distribution and magnitude of temperature that appear on the contact surfaces are applied pressure and the penetration. Besides that, it was found, that the penetration in high measure depends on the temperature, which proves the value of the coherence, which is almost equal to 1.
Investigation of thermal behavior of brake system using alternative materials
(2020) Stojanovic, Nadica; Abdullah, Oday; Glišović, Jasna; Grujic I.; Doric J.
© 2020 by Begell House, Inc. During the braking process many undesirable effects can appear that can disturb the safety of all participants in the traffic. It can be considered that using the new alternative friction materials is the key to improve the performance of brake system and reduce the negative effect on the environment. In this research paper, the temperatures and the stresses that appeared during the braking process will be investigated deeply. Different materials for braking disc [cast iron, aluminum matrix composites (AMC), and carbon–ceramics materials (CCM)] were used to achieve the numerical analysis. Finite element analysis (transient structural) was applied to obtain the numerical results. The results showed that the lowest temperature appeared during the heavy-duty braking process when using aluminum matrix composites, while the highest temperature appeared during the braking process when using different types of material for disc brake (cast iron and CCM). Also, the lowest stresses appeared during the braking process when using carbon–ceramics material. This study presents the criterion to select optimal material for braking discs based on the developed approach.
Numerical predictions of laminar flow and free convection heat transfer from an isothermal vertical flat plate
(2022) Belhocine A.; Stojanovic, Nadica; Abdullah, Oday
In this present work, the laminar free convection boundary layer flow of a two-dimensional fluid over the vertical flat plate with a uniform surface temperature has been numerically investigated in detail by the similarity solution method. The velocity and temperature profiles were considered similar to all values and their variations are as a function of distance from the leading edge measured along with the plate. By taking into account this thermal boundary condition, the system of governing partial differential equations is reduced to a system of non-linear ordinary differential equations. The latter was solved numerically using the Runge-Kutta method of the fourth-order, the solution of which was obtained by using the FORTRAN code on a computer. The numerical analysis resulting from this simulation allows us to derive some prescribed values of various material parameters involved in the problem to which several important results were discussed in depth such as velocity, temperature, and rate of heat transfer. The definitive comparison between the two numerical models showed us an excellent agreement concerning the order of precision of the simulation. Finally, we compared our numerical results with a certain model already treated, which is in the specialized literature.
Numerical Simulation of Laminar Boundary Layer Flow Over a Horizontal Flat Plate in External Incompressible Viscous Fluid
(2021) Belhocine A.; Stojanovic, Nadica; Abdullah, Oday
In this paper, steady laminar boundary layer flow of a Newtonian fluid over a flat plate in a uniform free stream was investigated numerically when the surface plate is heated by forced convection from the hot fluid. This flow is a good model of many situations involving flow over fins that are relatively widely spaced. All the solutions given here were with constant fluid properties and negligible viscous dissipation for two-dimensional, steady, incompressible laminar flow with zero pressure gradient. The similarity solution has shown its efficiency here to transform the governing equations of the thermal boundary layer into a nonlinear, third-order ordinary differential equation and solved numerically by using 4th-order Runge-Kutta method which in turn was programmed in FORTRAN language. The dimensionless temperature, velocity, and all boundary layer functions profiles were obtained and plotted in figures for different parameters entering into the problem. Several results of best approximations and expressions of important correlations relating to heat transfer rates were drawn in this study of which Prandtl’s number to the plate for physical interest was also discussed across the tables. The same case of solution procedure was made for a plane plate subjected to other thermal boundary conditions in a laminar flow. Finally, for the validation of the treated numerical model, the results obtained are in good agreement with those of the specialized literature, and comparison with available results in certain cases is excellent.
Particle formation due to brake wear, influence on the people health and measures for their reduction: a review
(2022) Stojanovic, Nadica; Glišović, Jasna; Abdullah, Oday; Belhocine A.; Grujic I.
For achieving the desired vehicle speed, the IC engine is very important, while for further vehicle speed maintaining and adaptation to road conditions, the braking system is important. With each brake’s activation, wear products are forming, which are very harmful to the environment, because they can contain heavy metals. The braking working parameters (initial speed and braking pressure) are beside the achieved temperature in contact par, the most responsible, for particle formation and their release into the air. The particles forming can be divided by size on coarse, fine, and ultrafine particles, and which were observed in the paper. However, the greatest accent was placed on coarse and fine particles. For the determination of the composition of wear products, most often, laboratory tests were used. Particle composition greatly depends on the composition of brake pads, which can consist of about 30 components, and where some of these components have very unfavourable effects on people’s health. So today, many researches are focused on finding such composition for brake pads, which will wear as less as possible, without disturbing the basic tribological properties. The conclusion of this paper shows that the applied materials for manufacturing the braking system are very important, as well as the construction, for the reduction of particle emission.
Particles formation due to the wear of tires and measures for the wear reduction: A review
(2021) Stojanovic, Nadica; Abdullah, Oday; Grujic I.; Boskovic B.
Tires are a very important part of a vehicle, necessary for the vehicle driving. During the vehicle exploitation, due to the friction which appears in the contact between the tire and the road, it comes to the formation of so called non-exhaust particles. The particles formed during the vehicle exploitation can be composed of heavy metals and they are harmful for people’s health and for the environment. Several factors influence the size of the wear of tires. The investigations about the tires behavior as well as the size of the wear can be conducted on the road, in the laboratory, as well as by application of modern software. The paper shows the applied methodologies applied by other researchers during the investigation of tires particles formation, the applied materials for the tires manufacturing, influential parameters on the wear of tires, as well as methods for the wear of tires reduction. After analyzing other researches in the subject field, the authors have come to the conclusions related to the factors which can reduce the wear of tires and these factors should be given proper attention in further studies.
PRESSURE INFLUENCE ON HEATING OF VENTILATING DISC BRAKES FOR PASSENGER CARS
(2020) Stojanovic, Nadica; Glišović, Jasna; Abdullah, Oday; Grujic, Ivan; Vasiljević, Saša
© 2020 Society of Thermal Engineers of Serbia. The braking system is one of the most important elements in vehicle systems from the aspect of vehicle safety, besides the steering system and the internal combustion engine. During the braking process, the disc and pads absorb a large amount of kinetic energy that converted to heat. Owing to this frictional heating, it is necessary to compute the temperature distribution that will be ap-peared during the braking process, which is the main goal of this research pa-per. There are many factors that can be influenced to the distribution of fric-tional heat generated. One of the significant factors is the applied pressure by the brake pad on the braking disc. The results proved that when increased the applied pressure then the frictional heat generated increased too. It was devel-oped a new finite element model based on observed data from real vehicle. It was used ANSYS/WORKBENCH 14.5 software to perform the numerical analy-sis, module Transient Structural. Parts that are the most disposed to the thermal stress are braking pads. Also, it was found time period from 0 to 0.1 second is the most critical period during the whole braking period, because in this period, temperature rises rapidly, the maximum temperature occurred at 1.338 sec-onds, and after that it falls.
Study the influence of repeated braking on the thermal behavior of brake system using experimental work
(2022) Stojanovic, Nadica; Grujic, Ivan; Glišović, Jasna; Abdullah, Oday
During the repeated braking, it will generate high amount of heat on the braking disc and braking pads. The value of the generated heat depends on many factors such as the vehicle speed, materials properties, disc brake construction, as well as the number of braking cycles. The aim of this paper is to investigate the effect of repeated braking on the temperature distribution of the braking pads and disc. It was performed the experimental approach under the laboratory conditions without air flow. It was found that the temperatures of disc and pads increase significantly with each new cycle of braking. It was found that magnitude of the friction coefficient has great influence to reduce the braking distance. The obtained experimental results can be applied in the design and manufacture the brake system of the automotive vehicles based on the safety factor of passengers. In the other words, keep the heat generation within the limit.
STUDY THE STRUCTURAL PROBLEM IN THE BRAKE SYSTEM APPLYING A DIFFERENT PRESSURE FUNCTIONS
(2019) Stojanovic, Nadica; Abdullah, Oday; Schlattmann J.; Grujic, Ivan; Glišović, Jasna
During every braking process, the wear in the contacting surfaces of brake disc and brake pads will be occurred. Therefore, it’s very important to investigate the effective parameters on the wear mechanism of the contacting surfaces, this is necessary because of the lifetime of the elements of brake is proportional directly with the rate of wear. In this research paper, the influence of the applied pressure function by which brake pads act on the brake disc is investigated using finite element method. Three different functions of pressure were applied which are: constant, linear and exponential. 3D model has been developed in order to analyze the penetration in the contacting surfaces of the elements of brake system. The results presented the variation of penetration with braking time. Furthermore, the results illustrated the distributions of the contact pressure in the fricti on pair (inner and outer sides) at any instant during the braking process. Also, it was found that the values of stress at the end of the braking process (regardless of the contact area) were the same for all functions of the applied pressure. The differences in the stresses occurred when applied different function of pressure function during the braking process.
The Effect of Applied Pressure Function on Thermo-elastic Problem in the Dry Friction Clutches
(2020) Stojanovic, Nadica; Abdullah, Oday; Rakisheva, Zaure; Lattieff F.; Hashim E.
© 2020, ASM International. The main purpose of this paper is to investigate deeply the effect the contact pressure function on the thermo-mechanical behavior of the friction clutch system during the slipping time (heating stage). The other purpose is to explore theoretically the complex interaction among the contact pressure, sliding speed and frictional characteristics of frictional facings to specify the magnitude and distribution of the frictional heating generation on the contact surfaces of the dry friction clutch under different applied pressure. It was developed a numerical code based on finite element method (ANSYS/APDL 2019) to determine accurately the contact pressure, temperature and frictional heat generated on contact surfaces of the friction clutch disc that has two effective frictional faces at any instant during the slipping period. It was found a significant effect of the magnitude and variation of applied pressure during the heating phase on the surface temperatures, contact pressure and frictional heat generated. Where, the hot spot can be appeared when the applied pressure is constant. Under such circumstances, high amount of temperature and contact pressure focused on a small zone of the nominal contact area. This phenomenon is considered one of the main reasons for the early failure of the contacting surfaces of friction clutch.
The influence of spoiler on the aerodynamic performances and longitudinal stability of the passenger car under high speed condition
(2022) Stojanovic, Nadica; Abdullah, Oday; Grujic I.; Glišović, Jasna; Belhocine A.
Abstract: Models of the passenger car without and with rear spoiler (types S1 and S2) are created using SolidWorks software. The ANSYS software/Fluid Flow (CFX) module was used to analyze deeply these models based on the numerical approach in order to achieve higher speed for vehicle with maintaining the stability of the car at the same time. Results of the numerical analysis proved that the spoiler has great influence on the longitudinal stability incensement, especially under high speeds conditions. While the shape of the spoiler is not significant factor on the stability. The lift force was reduced 7.6 times when used the spoiler (type S2) compared with to the vehicle without spoiler. While the drag force was increased 12% when used the spoiler (type S2). It was analyzed the influence of existence the rear spoiler on the passenger car, as well as the effect of the shape and construction dimensions of the spoiler on the longitudinal stability. It was developed integrated approach that included the design and numerical analysis of the vehicle stability. It was proved based on the developed approach how can reduced the negative effect of some factors in order to enhance the stability of the vehicle. Graphical Abstract: [Figure not available: see fulltext.].
The influence of the brake pad construction on noise formation, people’s health and reduction measures
(2022) Stojanovic, Nadica; Belhocine A.; Abdullah, Oday; Grujic, Ivan
The brake system is one of the most important systems on the vehicle, especially from the aspect of traffic safety. The use of the braking system comes with many undesirable effects, such as brake wear and noise emission. The noise that originates from brakes is related to the wear of brake elements, the applied materials for manufacture, to the elements which are connected to each other, and all of this represents a very challengeable problem in the automotive industry. In this paper are presented the dominant parameters that influence noise formation, where the main focus was placed on brake pads, as well as how the noise influences people’s health. After that, further, in the paper, it was analyzed the influence of the brake pads’ construction on the noise formation, and at the end are given the measures for noise reduction. The conclusions of the paper show that the construction of brake pads significantly influences noise emission, noise negatively influences on the people health, and because of the negative influence on the people health, some solutions show that it is necessary to include insulators in the construction of brake pads, and if the space in which people reside is observed, it is necessary during construction to use materials which will prevent noise conduction, into the space in which people reside.
The Influence of the Braking Disc Ribs and Applied Material on the Natural Frequency
(2022) Abdullah, Oday; Stojanovic, Nadica; Grujic I.
One of the important problems for which must be found an optimal solution is the noise that originate from vehicles. In this research paper, it was investigated deeply the effect of ribs shape and type of material on the noise of ventilated braking discs. Four different ventilated braking discs were selected to achieve the numerical analysis, all these brakes have the same overall dimensions, except the ribs shape is different. The materials used in this work are the cast iron, AMC and CCM for all four discs. The main aim of this paper is to find the optimal ribs shape, as well as the manufacturing material for the braking disc by applying Taguchi method. The percentage share of the ribs shapes as well as of applied material influence on the noise generation, were determined by applying Analysis of Variance—ANOVA. Finally, it was found that the material influence is most significant with 74.48%, while the ribs shape influence on the noise generation is 24.24%. The most optimal results obtained for the 2nd model which was made from CCM, compared with other suggested models.
The Influence Of The Hydrogen Injection Timing On The Internal Combustion Engine Working Cycle
(2021) Grujic, Ivan; Doric J.; Abdullah, Oday; Stojanovic, Nadica; Davinić, Aleksandar
From an ecological aspect, the hydrogen has all properties to be a very good fuel for internal combustion engines. However the high combustion speed, as well as the possibility of backfire, is inconvenient properties of port injection. In this paper, the influence of the injection timing on the internal combustion engine working cycle parameters (pressure and temperature) was investigated deeply. The investigation, of the injection timing influence on the internal combustion engine working cycle parameters, was performed numerically by application of ANSYS software. It was observed the geometry of the real engine with added pre chamber, in order of layer mixture formation and pressure damping, because of high combustion speed. The results are presented for four cases with different injection timing and the same spark timing. By earlier injection, the time for mixing rise as well as the possibility of homogenization and uniform mixture creation, in pre chamber and cylinder. This claim it is confirmed on the basis of obtaining pressure and pressure rise gradient, which are growing with earlier injection, because of hydrogen combustion characteristics in stoichiometric mixture. The higher pressures as well as the surface under the diagram are positive from the aspect of the engine efficiency. However, with the earlier injection, the values of the pressure rise gradient are higher than for the classic Diesel engine. This means that this phenomena can cause brutal engine work from the aspect of mechanical stresses. However the value of the maximum pressure is smaller than this in a Diesel engine, this is due to added pre chamber, which has decreased the compression ratio.
Three-dimensional finite element analysis of contact problem in dry friction clutches
(2021) sabri, laith; Stojanovic, Nadica; Senatore, Adolfo; Jweeg, Muhsin; Abed, Azher; Abdullah, Oday
We present an investigation through numerical analysis (FEM) of the solution of the contact problem in friction clutch systems during engagement manoeuver. The case of high contact pressure between the sliding elements of a clutch system (flywheel, friction clutch and pressure plate) has been also considered. A finite element model of a dry friction clutch system (single disc) to estimate the distributions of the contact pressure between the contact elements of the clutch system under different working conditions has been developed and the main findings are discussed. Furthermore, the effect of modules of elasticity (contact stiffness) on the distribution of contact pressure of the mating surfaces was investigated. Also, the results encompass the deformations of the contacting surfaces for different cases. This work could provide a fundamental intermediate step to obtain a partial solution to the thermos-elastic problem in order to compute the thermal-driven deformations and stresses in the automotive clutches and brakes under different working conditions.